from fontTools.misc.py23 import *
from fontTools.misc.textTools import safeEval, readHex
from fontTools.misc.encodingTools import getEncoding
from fontTools.ttLib import getSearchRange
from fontTools.unicode import Unicode
from . import DefaultTable
import sys
import struct
import array
import logging


log = logging.getLogger(__name__)


def _make_map(font, chars, gids):
	assert len(chars) == len(gids)
	cmap = {}
	glyphOrder = font.getGlyphOrder()
	for char,gid in zip(chars,gids):
		if gid is 0:
			continue
		try:
			name = glyphOrder[gid]
		except IndexError:
			name = font.getGlyphName(gid)
		cmap[char] = name
	return cmap

class table__c_m_a_p(DefaultTable.DefaultTable):

	def getcmap(self, platformID, platEncID):
		for subtable in self.tables:
			if (subtable.platformID == platformID and
					subtable.platEncID == platEncID):
				return subtable
		return None # not found

	def getBestCmap(self, cmapPreferences=((3, 10), (0, 6), (0, 4), (3, 1), (0, 3), (0, 2), (0, 1), (0, 0))):
		"""Return the 'best' unicode cmap dictionary available in the font,
		or None, if no unicode cmap subtable is available.

		By default it will search for the following (platformID, platEncID)
		pairs:
			(3, 10), (0, 6), (0, 4), (3, 1), (0, 3), (0, 2), (0, 1), (0, 0)
		This can be customized via the cmapPreferences argument.
		"""
		for platformID, platEncID in cmapPreferences:
			cmapSubtable = self.getcmap(platformID, platEncID)
			if cmapSubtable is not None:
				return cmapSubtable.cmap
		return None  # None of the requested cmap subtables were found

	def buildReversed(self):
		"""Returns a reverse cmap such as {'one':{0x31}, 'A':{0x41,0x391}}.

		The values are sets of Unicode codepoints because
		some fonts map different codepoints to the same glyph.
		For example, U+0041 LATIN CAPITAL LETTER A and U+0391
		GREEK CAPITAL LETTER ALPHA are sometimes the same glyph.
		"""
		result = {}
		for subtable in self.tables:
			if subtable.isUnicode():
				for codepoint, name in subtable.cmap.items():
					result.setdefault(name, set()).add(codepoint)
		return result

	def decompile(self, data, ttFont):
		tableVersion, numSubTables = struct.unpack(">HH", data[:4])
		self.tableVersion = int(tableVersion)
		self.tables = tables = []
		seenOffsets = {}
		for i in range(numSubTables):
			platformID, platEncID, offset = struct.unpack(
					">HHl", data[4+i*8:4+(i+1)*8])
			platformID, platEncID = int(platformID), int(platEncID)
			format, length = struct.unpack(">HH", data[offset:offset+4])
			if format in [8,10,12,13]:
				format, reserved, length = struct.unpack(">HHL", data[offset:offset+8])
			elif format in [14]:
				format, length = struct.unpack(">HL", data[offset:offset+6])

			if not length:
				log.error(
					"cmap subtable is reported as having zero length: platformID %s, "
					"platEncID %s, format %s offset %s. Skipping table.",
					platformID, platEncID, format, offset)
				continue
			table = CmapSubtable.newSubtable(format)
			table.platformID = platformID
			table.platEncID = platEncID
			# Note that by default we decompile only the subtable header info;
			# any other data gets decompiled only when an attribute of the
			# subtable is referenced.
			table.decompileHeader(data[offset:offset+int(length)], ttFont)
			if offset in seenOffsets:
				table.data = None # Mark as decompiled
				table.cmap = tables[seenOffsets[offset]].cmap
			else:
				seenOffsets[offset] = i
			tables.append(table)

	def compile(self, ttFont):
		self.tables.sort()  # sort according to the spec; see CmapSubtable.__lt__()
		numSubTables = len(self.tables)
		totalOffset = 4 + 8 * numSubTables
		data = struct.pack(">HH", self.tableVersion, numSubTables)
		tableData = b""
		seen = {}  # Some tables are the same object reference. Don't compile them twice.
		done = {}  # Some tables are different objects, but compile to the same data chunk
		for table in self.tables:
			try:
				offset = seen[id(table.cmap)]
			except KeyError:
				chunk = table.compile(ttFont)
				if chunk in done:
					offset = done[chunk]
				else:
					offset = seen[id(table.cmap)] = done[chunk] = totalOffset + len(tableData)
					tableData = tableData + chunk
			data = data + struct.pack(">HHl", table.platformID, table.platEncID, offset)
		return data + tableData

	def toXML(self, writer, ttFont):
		writer.simpletag("tableVersion", version=self.tableVersion)
		writer.newline()
		for table in self.tables:
			table.toXML(writer, ttFont)

	def fromXML(self, name, attrs, content, ttFont):
		if name == "tableVersion":
			self.tableVersion = safeEval(attrs["version"])
			return
		if name[:12] != "cmap_format_":
			return
		if not hasattr(self, "tables"):
			self.tables = []
		format = safeEval(name[12:])
		table = CmapSubtable.newSubtable(format)
		table.platformID = safeEval(attrs["platformID"])
		table.platEncID = safeEval(attrs["platEncID"])
		table.fromXML(name, attrs, content, ttFont)
		self.tables.append(table)


class CmapSubtable(object):

	@staticmethod
	def getSubtableClass(format):
		"""Return the subtable class for a format."""
		return cmap_classes.get(format, cmap_format_unknown)

	@staticmethod
	def newSubtable(format):
		"""Return a new instance of a subtable for format."""
		subtableClass = CmapSubtable.getSubtableClass(format)
		return subtableClass(format)

	def __init__(self, format):
		self.format = format
		self.data = None
		self.ttFont = None

	def __getattr__(self, attr):
		# allow lazy decompilation of subtables.
		if attr[:2] == '__': # don't handle requests for member functions like '__lt__'
			raise AttributeError(attr)
		if self.data is None:
			raise AttributeError(attr)
		self.decompile(None, None) # use saved data.
		self.data = None	# Once this table has been decompiled, make sure we don't
							# just return the original data. Also avoids recursion when
							# called with an attribute that the cmap subtable doesn't have.
		return getattr(self, attr)

	def decompileHeader(self, data, ttFont):
		format, length, language = struct.unpack(">HHH", data[:6])
		assert len(data) == length, "corrupt cmap table format %d (data length: %d, header length: %d)" % (format, len(data), length)
		self.format = int(format)
		self.length = int(length)
		self.language = int(language)
		self.data = data[6:]
		self.ttFont = ttFont

	def toXML(self, writer, ttFont):
		writer.begintag(self.__class__.__name__, [
				("platformID", self.platformID),
				("platEncID", self.platEncID),
				("language", self.language),
				])
		writer.newline()
		codes = sorted(self.cmap.items())
		self._writeCodes(codes, writer)
		writer.endtag(self.__class__.__name__)
		writer.newline()

	def getEncoding(self, default=None):
		"""Returns the Python encoding name for this cmap subtable based on its platformID,
		platEncID, and language.  If encoding for these values is not known, by default
		None is returned.  That can be overriden by passing a value to the default
		argument.

		Note that if you want to choose a "preferred" cmap subtable, most of the time
		self.isUnicode() is what you want as that one only returns true for the modern,
		commonly used, Unicode-compatible triplets, not the legacy ones.
		"""
		return getEncoding(self.platformID, self.platEncID, self.language, default)

	def isUnicode(self):
		return (self.platformID == 0 or
			(self.platformID == 3 and self.platEncID in [0, 1, 10]))

	def isSymbol(self):
		return self.platformID == 3 and self.platEncID == 0

	def _writeCodes(self, codes, writer):
		isUnicode = self.isUnicode()
		for code, name in codes:
			writer.simpletag("map", code=hex(code), name=name)
			if isUnicode:
				writer.comment(Unicode[code])
			writer.newline()

	def __lt__(self, other):
		if not isinstance(other, CmapSubtable):
			return NotImplemented

		# implemented so that list.sort() sorts according to the spec.
		selfTuple = (
			getattr(self, "platformID", None),
			getattr(self, "platEncID", None),
			getattr(self, "language", None),
			self.__dict__)
		otherTuple = (
			getattr(other, "platformID", None),
			getattr(other, "platEncID", None),
			getattr(other, "language", None),
			other.__dict__)
		return selfTuple < otherTuple


class cmap_format_0(CmapSubtable):

	def decompile(self, data, ttFont):
		# we usually get here indirectly from the subtable __getattr__ function, in which case both args must be None.
		# If not, someone is calling the subtable decompile() directly, and must provide both args.
		if data is not None and ttFont is not None:
			self.decompileHeader(data, ttFont)
		else:
			assert (data is None and ttFont is None), "Need both data and ttFont arguments"
		data = self.data # decompileHeader assigns the data after the header to self.data
		assert 262 == self.length, "Format 0 cmap subtable not 262 bytes"
		gids = array.array("B")
		gids.frombytes(self.data)
		charCodes = list(range(len(gids)))
		self.cmap = _make_map(self.ttFont, charCodes, gids)

	def compile(self, ttFont):
		if self.data:
			return struct.pack(">HHH", 0, 262, self.language) + self.data

		cmap = self.cmap
		assert set(cmap.keys()).issubset(range(256))
		getGlyphID = ttFont.getGlyphID
		valueList = [getGlyphID(cmap[i]) if i in cmap else 0 for i in range(256)]

		gids = array.array("B", valueList)
		data = struct.pack(">HHH", 0, 262, self.language) + gids.tobytes()
		assert len(data) == 262
		return data

	def fromXML(self, name, attrs, content, ttFont):
		self.language = safeEval(attrs["language"])
		if not hasattr(self, "cmap"):
			self.cmap = {}
		cmap = self.cmap
		for element in content:
			if not isinstance(element, tuple):
				continue
			name, attrs, content = element
			if name != "map":
				continue
			cmap[safeEval(attrs["code"])] = attrs["name"]


subHeaderFormat = ">HHhH"
class SubHeader(object):
	def __init__(self):
		self.firstCode = None
		self.entryCount = None
		self.idDelta = None
		self.idRangeOffset = None
		self.glyphIndexArray = []

class cmap_format_2(CmapSubtable):

	def setIDDelta(self, subHeader):
		subHeader.idDelta = 0
		# find the minGI which is not zero.
		minGI = subHeader.glyphIndexArray[0]
		for gid in subHeader.glyphIndexArray:
			if (gid != 0) and (gid < minGI):
				minGI = gid
		# The lowest gid in glyphIndexArray, after subtracting idDelta, must be 1.
		# idDelta is a short, and must be between -32K and 32K. minGI can be between 1 and 64K.
		# We would like to pick an idDelta such that the first glyphArray GID is 1,
		# so that we are more likely to be able to combine glypharray GID subranges.
		# This means that we have a problem when minGI is > 32K
		# Since the final gi is reconstructed from the glyphArray GID by:
		#    (short)finalGID = (gid + idDelta) % 0x10000),
		# we can get from a glypharray GID of 1 to a final GID of 65K by subtracting 2, and casting the
		# negative number to an unsigned short.

		if (minGI > 1):
			if minGI > 0x7FFF:
				subHeader.idDelta = -(0x10000 - minGI) -1
			else:
				subHeader.idDelta = minGI -1
			idDelta = subHeader.idDelta
			for i in range(subHeader.entryCount):
				gid = subHeader.glyphIndexArray[i]
				if gid > 0:
					subHeader.glyphIndexArray[i] = gid - idDelta

	def decompile(self, data, ttFont):
		# we usually get here indirectly from the subtable __getattr__ function, in which case both args must be None.
		# If not, someone is calling the subtable decompile() directly, and must provide both args.
		if data is not None and ttFont is not None:
			self.decompileHeader(data, ttFont)
		else:
			assert (data is None and ttFont is None), "Need both data and ttFont arguments"

		data = self.data # decompileHeader assigns the data after the header to self.data
		subHeaderKeys = []
		maxSubHeaderindex = 0
		# get the key array, and determine the number of subHeaders.
		allKeys = array.array("H")
		allKeys.frombytes(data[:512])
		data = data[512:]
		if sys.byteorder != "big": allKeys.byteswap()
		subHeaderKeys = [ key//8 for key in allKeys]
		maxSubHeaderindex = max(subHeaderKeys)

		#Load subHeaders
		subHeaderList = []
		pos = 0
		for i in range(maxSubHeaderindex + 1):
			subHeader = SubHeader()
			(subHeader.firstCode, subHeader.entryCount, subHeader.idDelta, \
				subHeader.idRangeOffset) = struct.unpack(subHeaderFormat, data[pos:pos + 8])
			pos += 8
			giDataPos = pos + subHeader.idRangeOffset-2
			giList = array.array("H")
			giList.frombytes(data[giDataPos:giDataPos + subHeader.entryCount*2])
			if sys.byteorder != "big": giList.byteswap()
			subHeader.glyphIndexArray = giList
			subHeaderList.append(subHeader)
		# How this gets processed.
		# Charcodes may be one or two bytes.
		# The first byte of a charcode is mapped through the subHeaderKeys, to select
		# a subHeader. For any subheader but 0, the next byte is then mapped through the
		# selected subheader. If subheader Index 0 is selected, then the byte itself is
		# mapped through the subheader, and there is no second byte.
		# Then assume that the subsequent byte is the first byte of the next charcode,and repeat.
		#
		# Each subheader references a range in the glyphIndexArray whose length is entryCount.
		# The range in glyphIndexArray referenced by a sunheader may overlap with the range in glyphIndexArray
		# referenced by another subheader.
		# The only subheader that will be referenced by more than one first-byte value is the subheader
		# that maps the entire range of glyphID values to glyphIndex 0, e.g notdef:
		#	 {firstChar 0, EntryCount 0,idDelta 0,idRangeOffset xx}
		# A byte being mapped though a subheader is treated as in index into a mapping of array index to font glyphIndex.
		# A subheader specifies a subrange within (0...256) by the
		# firstChar and EntryCount values. If the byte value is outside the subrange, then the glyphIndex is zero
		# (e.g. glyph not in font).
		# If the byte index is in the subrange, then an offset index is calculated as (byteIndex - firstChar).
		# The index to glyphIndex mapping is a subrange of the glyphIndexArray. You find the start of the subrange by
		# counting idRangeOffset bytes from the idRangeOffset word. The first value in this subrange is the
		# glyphIndex for the index firstChar. The offset index should then be used in this array to get the glyphIndex.
		# Example for Logocut-Medium
		# first byte of charcode = 129; selects subheader 1.
		# subheader 1 = {firstChar 64, EntryCount 108,idDelta 42,idRangeOffset 0252}
		# second byte of charCode = 66
		# the index offset = 66-64 = 2.
		# The subrange of the glyphIndexArray starting at 0x0252 bytes from the idRangeOffset word is:
		# [glyphIndexArray index], [subrange array index] = glyphIndex
		# [256], [0]=1 	from charcode [129, 64]
		# [257], [1]=2  	from charcode [129, 65]
		# [258], [2]=3  	from charcode [129, 66]
		# [259], [3]=4  	from charcode [129, 67]
		# So, the glyphIndex = 3 from the array. Then if idDelta is not zero and the glyph ID is not zero,
		# add it to the glyphID to get the final glyphIndex
		# value. In this case the final glyph index = 3+ 42 -> 45 for the final glyphIndex. Whew!

		self.data = b""
		cmap = {}
		notdefGI = 0
		for firstByte in range(256):
			subHeadindex = subHeaderKeys[firstByte]
			subHeader = subHeaderList[subHeadindex]
			if subHeadindex == 0:
				if (firstByte < subHeader.firstCode) or (firstByte >= subHeader.firstCode + subHeader.entryCount):
					continue # gi is notdef.
				else:
					charCode = firstByte
					offsetIndex = firstByte - subHeader.firstCode
					gi = subHeader.glyphIndexArray[offsetIndex]
					if gi != 0:
						gi = (gi + subHeader.idDelta) % 0x10000
					else:
						continue # gi is notdef.
				cmap[charCode] = gi
			else:
				if subHeader.entryCount:
					charCodeOffset = firstByte * 256 + subHeader.firstCode
					for offsetIndex in range(subHeader.entryCount):
						charCode = charCodeOffset + offsetIndex
						gi = subHeader.glyphIndexArray[offsetIndex]
						if gi != 0:
							gi = (gi + subHeader.idDelta) % 0x10000
						else:
							continue
						cmap[charCode] = gi
				# If not subHeader.entryCount, then all char codes with this first byte are
				# mapped to .notdef. We can skip this subtable, and leave the glyphs un-encoded, which is the
				# same as mapping it to .notdef.

		gids = list(cmap.values())
		charCodes = list(cmap.keys())
		self.cmap = _make_map(self.ttFont, charCodes, gids)

	def compile(self, ttFont):
		if self.data:
			return struct.pack(">HHH", self.format, self.length, self.language) + self.data
		kEmptyTwoCharCodeRange = -1
		notdefGI = 0

		items = sorted(self.cmap.items())
		charCodes = [item[0] for item in items]
		names = [item[1] for item in items]
		nameMap = ttFont.getReverseGlyphMap()
		try:
			gids = [nameMap[name] for name in names]
		except KeyError:
			nameMap = ttFont.getReverseGlyphMap(rebuild=True)
			try:
				gids = [nameMap[name] for name in names]
			except KeyError:
				# allow virtual GIDs in format 2 tables
				gids = []
				for name in names:
					try:
						gid = nameMap[name]
					except KeyError:
						try:
							if (name[:3] == 'gid'):
								gid = int(name[3:])
							else:
								gid = ttFont.getGlyphID(name)
						except:
							raise KeyError(name)

					gids.append(gid)

		# Process the (char code to gid) item list in char code order.
		# By definition, all one byte char codes map to subheader 0.
		# For all the two byte char codes, we assume that the first byte maps maps to the empty subhead (with an entry count of 0,
		# which defines all char codes in its range to map to notdef) unless proven otherwise.
		# Note that since the char code items are processed in char code order, all the char codes with the
		# same first byte are in sequential order.

		subHeaderKeys = [kEmptyTwoCharCodeRange for x in range(256)] # list of indices into subHeaderList.
		subHeaderList = []

		# We force this subheader entry 0 to exist in the subHeaderList in the case where some one comes up
		# with a cmap where all the one byte char codes map to notdef,
		# with the result that the subhead 0 would not get created just by processing the item list.
		charCode = charCodes[0]
		if charCode > 255:
			subHeader = SubHeader()
			subHeader.firstCode = 0
			subHeader.entryCount = 0
			subHeader.idDelta = 0
			subHeader.idRangeOffset = 0
			subHeaderList.append(subHeader)

		lastFirstByte = -1
		items = zip(charCodes, gids)
		for charCode, gid in items:
			if gid == 0:
				continue
			firstbyte = charCode >> 8
			secondByte = charCode & 0x00FF

			if firstbyte != lastFirstByte: # Need to update the current subhead, and start a new one.
				if lastFirstByte > -1:
					# fix GI's and iDelta of current subheader.
					self.setIDDelta(subHeader)

					# If it was sunheader 0 for one-byte charCodes, then we need to set the subHeaderKeys value to zero
					# for the indices matching the char codes.
					if lastFirstByte == 0:
						for index in range(subHeader.entryCount):
							charCode = subHeader.firstCode + index
							subHeaderKeys[charCode] = 0

					assert (subHeader.entryCount == len(subHeader.glyphIndexArray)), "Error - subhead entry count does not match len of glyphID subrange."
				# init new subheader
				subHeader = SubHeader()
				subHeader.firstCode = secondByte
				subHeader.entryCount = 1
				subHeader.glyphIndexArray.append(gid)
				subHeaderList.append(subHeader)
				subHeaderKeys[firstbyte] = len(subHeaderList) -1
				lastFirstByte = firstbyte
			else:
				# need to fill in with notdefs all the code points between the last charCode and the current charCode.
				codeDiff = secondByte - (subHeader.firstCode + subHeader.entryCount)
				for i in range(codeDiff):
					subHeader.glyphIndexArray.append(notdefGI)
				subHeader.glyphIndexArray.append(gid)
				subHeader.entryCount = subHeader.entryCount + codeDiff + 1

		# fix GI's and iDelta of last subheader that we we added to the subheader array.
		self.setIDDelta(subHeader)

		# Now we add a final subheader for the subHeaderKeys which maps to empty two byte charcode ranges.
		subHeader = SubHeader()
		subHeader.firstCode = 0
		subHeader.entryCount = 0
		subHeader.idDelta = 0
		subHeader.idRangeOffset = 2
		subHeaderList.append(subHeader)
		emptySubheadIndex = len(subHeaderList) - 1
		for index in range(256):
			if subHeaderKeys[index] == kEmptyTwoCharCodeRange:
				subHeaderKeys[index] = emptySubheadIndex
		# Since this is the last subheader, the GlyphIndex Array starts two bytes after the start of the
		# idRangeOffset word of this subHeader. We can safely point to the first entry in the GlyphIndexArray,
		# since the first subrange of the GlyphIndexArray is for subHeader 0, which always starts with
		# charcode 0 and GID 0.

		idRangeOffset = (len(subHeaderList)-1)*8 + 2 # offset to beginning of glyphIDArray from first subheader idRangeOffset.
		subheadRangeLen = len(subHeaderList) -1 # skip last special empty-set subheader; we've already hardocodes its idRangeOffset to 2.
		for index in range(subheadRangeLen):
			subHeader = subHeaderList[index]
			subHeader.idRangeOffset = 0
			for j in range(index):
				prevSubhead = subHeaderList[j]
				if prevSubhead.glyphIndexArray == subHeader.glyphIndexArray: # use the glyphIndexArray subarray
					subHeader.idRangeOffset = prevSubhead.idRangeOffset - (index-j)*8
					subHeader.glyphIndexArray = []
					break
			if subHeader.idRangeOffset == 0: # didn't find one.
				subHeader.idRangeOffset = idRangeOffset
				idRangeOffset = (idRangeOffset - 8) + subHeader.entryCount*2 # one less subheader, one more subArray.
			else:
				idRangeOffset = idRangeOffset - 8  # one less subheader

		# Now we can write out the data!
		length = 6 + 512 + 8*len(subHeaderList) # header, 256 subHeaderKeys, and subheader array.
		for subhead in 	subHeaderList[:-1]:
			length = length + len(subhead.glyphIndexArray)*2  # We can't use subhead.entryCount, as some of the subhead may share subArrays.
		dataList = [struct.pack(">HHH", 2, length, self.language)]
		for index in subHeaderKeys:
			dataList.append(struct.pack(">H", index*8))
		for subhead in 	subHeaderList:
			dataList.append(struct.pack(subHeaderFormat, subhead.firstCode, subhead.entryCount, subhead.idDelta, subhead.idRangeOffset))
		for subhead in 	subHeaderList[:-1]:
			for gi in subhead.glyphIndexArray:
				dataList.append(struct.pack(">H", gi))
		data = bytesjoin(dataList)
		assert (len(data) == length), "Error: cmap format 2 is not same length as calculated! actual: " + str(len(data))+ " calc : " + str(length)
		return data

	def fromXML(self, name, attrs, content, ttFont):
		self.language = safeEval(attrs["language"])
		if not hasattr(self, "cmap"):
			self.cmap = {}
		cmap = self.cmap

		for element in content:
			if not isinstance(element, tuple):
				continue
			name, attrs, content = element
			if name != "map":
				continue
			cmap[safeEval(attrs["code"])] = attrs["name"]


cmap_format_4_format = ">7H"

#uint16  endCode[segCount]          # Ending character code for each segment, last = 0xFFFF.
#uint16  reservedPad                # This value should be zero
#uint16  startCode[segCount]        # Starting character code for each segment
#uint16  idDelta[segCount]          # Delta for all character codes in segment
#uint16  idRangeOffset[segCount]    # Offset in bytes to glyph indexArray, or 0
#uint16  glyphIndexArray[variable]  # Glyph index array

def splitRange(startCode, endCode, cmap):
	# Try to split a range of character codes into subranges with consecutive
	# glyph IDs in such a way that the cmap4 subtable can be stored "most"
	# efficiently. I can't prove I've got the optimal solution, but it seems
	# to do well with the fonts I tested: none became bigger, many became smaller.
	if startCode == endCode:
		return [], [endCode]

	lastID = cmap[startCode]
	lastCode = startCode
	inOrder = None
	orderedBegin = None
	subRanges = []

	# Gather subranges in which the glyph IDs are consecutive.
	for code in range(startCode + 1, endCode + 1):
		glyphID = cmap[code]

		if glyphID - 1 == lastID:
			if inOrder is None or not inOrder:
				inOrder = 1
				orderedBegin = lastCode
		else:
			if inOrder:
				inOrder = 0
				subRanges.append((orderedBegin, lastCode))
				orderedBegin = None

		lastID = glyphID
		lastCode = code

	if inOrder:
		subRanges.append((orderedBegin, lastCode))
	assert lastCode == endCode

	# Now filter out those new subranges that would only make the data bigger.
	# A new segment cost 8 bytes, not using a new segment costs 2 bytes per
	# character.
	newRanges = []
	for b, e in subRanges:
		if b == startCode and e == endCode:
			break  # the whole range, we're fine
		if b == startCode or e == endCode:
			threshold = 4  # split costs one more segment
		else:
			threshold = 8  # split costs two more segments
		if (e - b + 1) > threshold:
			newRanges.append((b, e))
	subRanges = newRanges

	if not subRanges:
		return [], [endCode]

	if subRanges[0][0] != startCode:
		subRanges.insert(0, (startCode, subRanges[0][0] - 1))
	if subRanges[-1][1] != endCode:
		subRanges.append((subRanges[-1][1] + 1, endCode))

	# Fill the "holes" in the segments list -- those are the segments in which
	# the glyph IDs are _not_ consecutive.
	i = 1
	while i < len(subRanges):
		if subRanges[i-1][1] + 1 != subRanges[i][0]:
			subRanges.insert(i, (subRanges[i-1][1] + 1, subRanges[i][0] - 1))
			i = i + 1
		i = i + 1

	# Transform the ranges into startCode/endCode lists.
	start = []
	end = []
	for b, e in subRanges:
		start.append(b)
		end.append(e)
	start.pop(0)

	assert len(start) + 1 == len(end)
	return start, end


class cmap_format_4(CmapSubtable):

	def decompile(self, data, ttFont):
		# we usually get here indirectly from the subtable __getattr__ function, in which case both args must be None.
		# If not, someone is calling the subtable decompile() directly, and must provide both args.
		if data is not None and ttFont is not None:
			self.decompileHeader(data, ttFont)
		else:
			assert (data is None and ttFont is None), "Need both data and ttFont arguments"

		data = self.data # decompileHeader assigns the data after the header to self.data
		(segCountX2, searchRange, entrySelector, rangeShift) = \
					struct.unpack(">4H", data[:8])
		data = data[8:]
		segCount = segCountX2 // 2

		allCodes = array.array("H")
		allCodes.frombytes(data)
		self.data = data = None

		if sys.byteorder != "big": allCodes.byteswap()

		# divide the data
		endCode = allCodes[:segCount]
		allCodes = allCodes[segCount+1:]  # the +1 is skipping the reservedPad field
		startCode = allCodes[:segCount]
		allCodes = allCodes[segCount:]
		idDelta = allCodes[:segCount]
		allCodes = allCodes[segCount:]
		idRangeOffset = allCodes[:segCount]
		glyphIndexArray = allCodes[segCount:]
		lenGIArray = len(glyphIndexArray)

		# build 2-byte character mapping
		charCodes = []
		gids = []
		for i in range(len(startCode) - 1):	# don't do 0xffff!
			start = startCode[i]
			delta = idDelta[i]
			rangeOffset = idRangeOffset[i]
			# *someone* needs to get killed.
			partial = rangeOffset // 2 - start + i - len(idRangeOffset)

			rangeCharCodes = list(range(startCode[i], endCode[i] + 1))
			charCodes.extend(rangeCharCodes)
			if rangeOffset == 0:
				gids.extend([(charCode + delta) & 0xFFFF for charCode in rangeCharCodes])
			else:
				for charCode in rangeCharCodes:
					index = charCode + partial
					assert (index < lenGIArray), "In format 4 cmap, range (%d), the calculated index (%d) into the glyph index array is not less than the length of the array (%d) !" % (i, index, lenGIArray)
					if glyphIndexArray[index] != 0:  # if not missing glyph
						glyphID = glyphIndexArray[index] + delta
					else:
						glyphID = 0  # missing glyph
					gids.append(glyphID & 0xFFFF)

		self.cmap = _make_map(self.ttFont, charCodes, gids)

	def compile(self, ttFont):
		if self.data:
			return struct.pack(">HHH", self.format, self.length, self.language) + self.data

		charCodes = list(self.cmap.keys())
		if not charCodes:
			startCode = [0xffff]
			endCode = [0xffff]
		else:
			charCodes.sort()
			names = [self.cmap[code] for code in charCodes]
			nameMap = ttFont.getReverseGlyphMap()
			try:
				gids = [nameMap[name] for name in names]
			except KeyError:
				nameMap = ttFont.getReverseGlyphMap(rebuild=True)
				try:
					gids = [nameMap[name] for name in names]
				except KeyError:
					# allow virtual GIDs in format 4 tables
					gids = []
					for name in names:
						try:
							gid = nameMap[name]
						except KeyError:
							try:
								if (name[:3] == 'gid'):
									gid = int(name[3:])
								else:
									gid = ttFont.getGlyphID(name)
							except:
								raise KeyError(name)

						gids.append(gid)
			cmap = {}  # code:glyphID mapping
			for code, gid in zip(charCodes, gids):
				cmap[code] = gid

			# Build startCode and endCode lists.
			# Split the char codes in ranges of consecutive char codes, then split
			# each range in more ranges of consecutive/not consecutive glyph IDs.
			# See splitRange().
			lastCode = charCodes[0]
			endCode = []
			startCode = [lastCode]
			for charCode in charCodes[1:]:  # skip the first code, it's the first start code
				if charCode == lastCode + 1:
					lastCode = charCode
					continue
				start, end = splitRange(startCode[-1], lastCode, cmap)
				startCode.extend(start)
				endCode.extend(end)
				startCode.append(charCode)
				lastCode = charCode
			start, end = splitRange(startCode[-1], lastCode, cmap)
			startCode.extend(start)
			endCode.extend(end)
			startCode.append(0xffff)
			endCode.append(0xffff)

		# build up rest of cruft
		idDelta = []
		idRangeOffset = []
		glyphIndexArray = []
		for i in range(len(endCode)-1):  # skip the closing codes (0xffff)
			indices = []
			for charCode in range(startCode[i], endCode[i] + 1):
				indices.append(cmap[charCode])
			if (indices == list(range(indices[0], indices[0] + len(indices)))):
				idDelta.append((indices[0] - startCode[i]) % 0x10000)
				idRangeOffset.append(0)
			else:
				# someone *definitely* needs to get killed.
				idDelta.append(0)
				idRangeOffset.append(2 * (len(endCode) + len(glyphIndexArray) - i))
				glyphIndexArray.extend(indices)
		idDelta.append(1)  # 0xffff + 1 == (tadaa!) 0. So this end code maps to .notdef
		idRangeOffset.append(0)

		# Insane.
		segCount = len(endCode)
		segCountX2 = segCount * 2
		searchRange, entrySelector, rangeShift = getSearchRange(segCount, 2)

		charCodeArray = array.array("H", endCode + [0] + startCode)
		idDeltaArray = array.array("H", idDelta)
		restArray = array.array("H", idRangeOffset + glyphIndexArray)
		if sys.byteorder != "big": charCodeArray.byteswap()
		if sys.byteorder != "big": idDeltaArray.byteswap()
		if sys.byteorder != "big": restArray.byteswap()
		data = charCodeArray.tobytes() + idDeltaArray.tobytes() + restArray.tobytes()

		length = struct.calcsize(cmap_format_4_format) + len(data)
		header = struct.pack(cmap_format_4_format, self.format, length, self.language,
				segCountX2, searchRange, entrySelector, rangeShift)
		return header + data

	def fromXML(self, name, attrs, content, ttFont):
		self.language = safeEval(attrs["language"])
		if not hasattr(self, "cmap"):
			self.cmap = {}
		cmap = self.cmap

		for element in content:
			if not isinstance(element, tuple):
				continue
			nameMap, attrsMap, dummyContent = element
			if nameMap != "map":
				assert 0, "Unrecognized keyword in cmap subtable"
			cmap[safeEval(attrsMap["code"])] = attrsMap["name"]


class cmap_format_6(CmapSubtable):

	def decompile(self, data, ttFont):
		# we usually get here indirectly from the subtable __getattr__ function, in which case both args must be None.
		# If not, someone is calling the subtable decompile() directly, and must provide both args.
		if data is not None and ttFont is not None:
			self.decompileHeader(data, ttFont)
		else:
			assert (data is None and ttFont is None), "Need both data and ttFont arguments"

		data = self.data # decompileHeader assigns the data after the header to self.data
		firstCode, entryCount = struct.unpack(">HH", data[:4])
		firstCode = int(firstCode)
		data = data[4:]
		#assert len(data) == 2 * entryCount  # XXX not true in Apple's Helvetica!!!
		gids = array.array("H")
		gids.frombytes(data[:2 * int(entryCount)])
		if sys.byteorder != "big": gids.byteswap()
		self.data = data = None

		charCodes = list(range(firstCode, firstCode + len(gids)))
		self.cmap = _make_map(self.ttFont, charCodes, gids)

	def compile(self, ttFont):
		if self.data:
			return struct.pack(">HHH", self.format, self.length, self.language) + self.data
		cmap = self.cmap
		codes = sorted(cmap.keys())
		if codes: # yes, there are empty cmap tables.
			codes = list(range(codes[0], codes[-1] + 1))
			firstCode = codes[0]
			valueList = [
				ttFont.getGlyphID(cmap[code]) if code in cmap else 0
				for code in codes
			]
			gids = array.array("H", valueList)
			if sys.byteorder != "big": gids.byteswap()
			data = gids.tobytes()
		else:
			data = b""
			firstCode = 0
		header = struct.pack(">HHHHH",
				6, len(data) + 10, self.language, firstCode, len(codes))
		return header + data

	def fromXML(self, name, attrs, content, ttFont):
		self.language = safeEval(attrs["language"])
		if not hasattr(self, "cmap"):
			self.cmap = {}
		cmap = self.cmap

		for element in content:
			if not isinstance(element, tuple):
				continue
			name, attrs, content = element
			if name != "map":
				continue
			cmap[safeEval(attrs["code"])] = attrs["name"]


class cmap_format_12_or_13(CmapSubtable):

	def __init__(self, format):
		self.format = format
		self.reserved = 0
		self.data = None
		self.ttFont = None

	def decompileHeader(self, data, ttFont):
		format, reserved, length, language, nGroups = struct.unpack(">HHLLL", data[:16])
		assert len(data) == (16 + nGroups*12) == (length), "corrupt cmap table format %d (data length: %d, header length: %d)" % (self.format, len(data), length)
		self.format = format
		self.reserved = reserved
		self.length = length
		self.language = language
		self.nGroups = nGroups
		self.data = data[16:]
		self.ttFont = ttFont

	def decompile(self, data, ttFont):
		# we usually get here indirectly from the subtable __getattr__ function, in which case both args must be None.
		# If not, someone is calling the subtable decompile() directly, and must provide both args.
		if data is not None and ttFont is not None:
			self.decompileHeader(data, ttFont)
		else:
			assert (data is None and ttFont is None), "Need both data and ttFont arguments"

		data = self.data # decompileHeader assigns the data after the header to self.data
		charCodes = []
		gids = []
		pos = 0
		for i in range(self.nGroups):
			startCharCode, endCharCode, glyphID = struct.unpack(">LLL",data[pos:pos+12] )
			pos += 12
			lenGroup = 1 + endCharCode - startCharCode
			charCodes.extend(list(range(startCharCode, endCharCode +1)))
			gids.extend(self._computeGIDs(glyphID, lenGroup))
		self.data = data = None
		self.cmap = _make_map(self.ttFont, charCodes, gids)

	def compile(self, ttFont):
		if self.data:
			return struct.pack(">HHLLL", self.format, self.reserved, self.length, self.language, self.nGroups) + self.data
		charCodes = list(self.cmap.keys())
		names = list(self.cmap.values())
		nameMap = ttFont.getReverseGlyphMap()
		try:
			gids = [nameMap[name] for name in names]
		except KeyError:
			nameMap = ttFont.getReverseGlyphMap(rebuild=True)
			try:
				gids = [nameMap[name] for name in names]
			except KeyError:
				# allow virtual GIDs in format 12 tables
				gids = []
				for name in names:
					try:
						gid = nameMap[name]
					except KeyError:
						try:
							if (name[:3] == 'gid'):
								gid = int(name[3:])
							else:
								gid = ttFont.getGlyphID(name)
						except:
							raise KeyError(name)

					gids.append(gid)

		cmap = {}  # code:glyphID mapping
		for code, gid in zip(charCodes, gids):
			cmap[code] = gid

		charCodes.sort()
		index = 0
		startCharCode = charCodes[0]
		startGlyphID = cmap[startCharCode]
		lastGlyphID = startGlyphID - self._format_step
		lastCharCode = startCharCode - 1
		nGroups = 0
		dataList = []
		maxIndex = len(charCodes)
		for index in range(maxIndex):
			charCode = charCodes[index]
			glyphID = cmap[charCode]
			if not self._IsInSameRun(glyphID, lastGlyphID, charCode, lastCharCode):
				dataList.append(struct.pack(">LLL", startCharCode, lastCharCode, startGlyphID))
				startCharCode = charCode
				startGlyphID = glyphID
				nGroups = nGroups + 1
			lastGlyphID = glyphID
			lastCharCode = charCode
		dataList.append(struct.pack(">LLL", startCharCode, lastCharCode, startGlyphID))
		nGroups = nGroups + 1
		data = bytesjoin(dataList)
		lengthSubtable = len(data) +16
		assert len(data) == (nGroups*12) == (lengthSubtable-16)
		return struct.pack(">HHLLL", self.format, self.reserved, lengthSubtable, self.language, nGroups) + data

	def toXML(self, writer, ttFont):
		writer.begintag(self.__class__.__name__, [
				("platformID", self.platformID),
				("platEncID", self.platEncID),
				("format", self.format),
				("reserved", self.reserved),
				("length", self.length),
				("language", self.language),
				("nGroups", self.nGroups),
				])
		writer.newline()
		codes = sorted(self.cmap.items())
		self._writeCodes(codes, writer)
		writer.endtag(self.__class__.__name__)
		writer.newline()

	def fromXML(self, name, attrs, content, ttFont):
		self.format = safeEval(attrs["format"])
		self.reserved = safeEval(attrs["reserved"])
		self.length = safeEval(attrs["length"])
		self.language = safeEval(attrs["language"])
		self.nGroups = safeEval(attrs["nGroups"])
		if not hasattr(self, "cmap"):
			self.cmap = {}
		cmap = self.cmap

		for element in content:
			if not isinstance(element, tuple):
				continue
			name, attrs, content = element
			if name != "map":
				continue
			cmap[safeEval(attrs["code"])] = attrs["name"]


class cmap_format_12(cmap_format_12_or_13):

	_format_step = 1

	def __init__(self, format=12):
		cmap_format_12_or_13.__init__(self, format)

	def _computeGIDs(self, startingGlyph, numberOfGlyphs):
		return list(range(startingGlyph, startingGlyph + numberOfGlyphs))

	def _IsInSameRun(self, glyphID, lastGlyphID, charCode, lastCharCode):
		return (glyphID == 1 + lastGlyphID) and (charCode == 1 + lastCharCode)


class cmap_format_13(cmap_format_12_or_13):

	_format_step = 0

	def __init__(self, format=13):
		cmap_format_12_or_13.__init__(self, format)

	def _computeGIDs(self, startingGlyph, numberOfGlyphs):
		return [startingGlyph] * numberOfGlyphs

	def _IsInSameRun(self, glyphID, lastGlyphID, charCode, lastCharCode):
		return (glyphID == lastGlyphID) and (charCode == 1 + lastCharCode)


def cvtToUVS(threeByteString):
	data = b"\0" + threeByteString
	val, = struct.unpack(">L", data)
	return val

def cvtFromUVS(val):
	assert 0 <= val < 0x1000000
	fourByteString = struct.pack(">L", val)
	return fourByteString[1:]


class cmap_format_14(CmapSubtable):

	def decompileHeader(self, data, ttFont):
		format, length, numVarSelectorRecords = struct.unpack(">HLL", data[:10])
		self.data = data[10:]
		self.length = length
		self.numVarSelectorRecords = numVarSelectorRecords
		self.ttFont = ttFont
		self.language = 0xFF # has no language.

	def decompile(self, data, ttFont):
		if data is not None and ttFont is not None:
			self.decompileHeader(data, ttFont)
		else:
			assert (data is None and ttFont is None), "Need both data and ttFont arguments"
		data = self.data

		self.cmap = {} # so that clients that expect this to exist in a cmap table won't fail.
		uvsDict = {}
		recOffset = 0
		for n in range(self.numVarSelectorRecords):
			uvs, defOVSOffset, nonDefUVSOffset = struct.unpack(">3sLL", data[recOffset:recOffset +11])
			recOffset += 11
			varUVS = cvtToUVS(uvs)
			if defOVSOffset:
				startOffset = defOVSOffset - 10
				numValues, = struct.unpack(">L", data[startOffset:startOffset+4])
				startOffset +=4
				for r in range(numValues):
					uv, addtlCnt = struct.unpack(">3sB", data[startOffset:startOffset+4])
					startOffset += 4
					firstBaseUV = cvtToUVS(uv)
					cnt = addtlCnt+1
					baseUVList = list(range(firstBaseUV, firstBaseUV+cnt))
					glyphList = [None]*cnt
					localUVList = zip(baseUVList, glyphList)
					try:
						uvsDict[varUVS].extend(localUVList)
					except KeyError:
						uvsDict[varUVS] = list(localUVList)

			if nonDefUVSOffset:
				startOffset = nonDefUVSOffset - 10
				numRecs, = struct.unpack(">L", data[startOffset:startOffset+4])
				startOffset +=4
				localUVList = []
				for r in range(numRecs):
					uv, gid = struct.unpack(">3sH", data[startOffset:startOffset+5])
					startOffset += 5
					uv = cvtToUVS(uv)
					glyphName = self.ttFont.getGlyphName(gid)
					localUVList.append((uv, glyphName))
				try:
					uvsDict[varUVS].extend(localUVList)
				except KeyError:
					uvsDict[varUVS] = localUVList

		self.uvsDict = uvsDict

	def toXML(self, writer, ttFont):
		writer.begintag(self.__class__.__name__, [
				("platformID", self.platformID),
				("platEncID", self.platEncID),
				])
		writer.newline()
		uvsDict = self.uvsDict
		uvsList = sorted(uvsDict.keys())
		for uvs in uvsList:
			uvList = uvsDict[uvs]
			uvList.sort(key=lambda item: (item[1] is not None, item[0], item[1]))
			for uv, gname in uvList:
				attrs = [("uv", hex(uv)), ("uvs", hex(uvs))]
				if gname is not None:
					attrs.append(("name", gname))
				writer.simpletag("map", attrs)
				writer.newline()
		writer.endtag(self.__class__.__name__)
		writer.newline()

	def fromXML(self, name, attrs, content, ttFont):
		self.language = 0xFF # provide a value so that CmapSubtable.__lt__() won't fail
		if not hasattr(self, "cmap"):
			self.cmap = {} # so that clients that expect this to exist in a cmap table won't fail.
		if not hasattr(self, "uvsDict"):
			self.uvsDict = {}
			uvsDict = self.uvsDict

		# For backwards compatibility reasons we accept "None" as an indicator
		# for "default mapping", unless the font actually has a glyph named
		# "None".
		_hasGlyphNamedNone = None

		for element in content:
			if not isinstance(element, tuple):
				continue
			name, attrs, content = element
			if name != "map":
				continue
			uvs = safeEval(attrs["uvs"])
			uv = safeEval(attrs["uv"])
			gname = attrs.get("name")
			if gname == "None":
				if _hasGlyphNamedNone is None:
					_hasGlyphNamedNone = "None" in ttFont.getGlyphOrder()
				if not _hasGlyphNamedNone:
					gname = None
			try:
				uvsDict[uvs].append((uv, gname))
			except KeyError:
				uvsDict[uvs] = [(uv, gname)]

	def compile(self, ttFont):
		if self.data:
			return struct.pack(">HLL", self.format, self.length, self.numVarSelectorRecords) + self.data

		uvsDict = self.uvsDict
		uvsList = sorted(uvsDict.keys())
		self.numVarSelectorRecords = len(uvsList)
		offset = 10 + self.numVarSelectorRecords*11 # current value is end of VarSelectorRecords block.
		data = []
		varSelectorRecords =[]
		for uvs in uvsList:
			entryList = uvsDict[uvs]

			defList = [entry for entry in entryList if entry[1] is None]
			if defList:
				defList = [entry[0] for entry in defList]
				defOVSOffset = offset
				defList.sort()

				lastUV = defList[0]
				cnt = -1
				defRecs = []
				for defEntry in defList:
					cnt +=1
					if (lastUV+cnt) != defEntry:
						rec = struct.pack(">3sB", cvtFromUVS(lastUV), cnt-1)
						lastUV = defEntry
						defRecs.append(rec)
						cnt = 0

				rec = struct.pack(">3sB", cvtFromUVS(lastUV), cnt)
				defRecs.append(rec)

				numDefRecs = len(defRecs)
				data.append(struct.pack(">L", numDefRecs))
				data.extend(defRecs)
				offset += 4 + numDefRecs*4
			else:
				defOVSOffset = 0

			ndefList = [entry for entry in entryList if entry[1] is not None]
			if ndefList:
				nonDefUVSOffset = offset
				ndefList.sort()
				numNonDefRecs = len(ndefList)
				data.append(struct.pack(">L", numNonDefRecs))
				offset += 4 + numNonDefRecs*5

				for uv, gname in ndefList:
					gid = ttFont.getGlyphID(gname)
					ndrec = struct.pack(">3sH", cvtFromUVS(uv), gid)
					data.append(ndrec)
			else:
				nonDefUVSOffset = 0

			vrec = struct.pack(">3sLL", cvtFromUVS(uvs), defOVSOffset, nonDefUVSOffset)
			varSelectorRecords.append(vrec)

		data = bytesjoin(varSelectorRecords) + bytesjoin(data)
		self.length = 10 + len(data)
		headerdata = struct.pack(">HLL", self.format, self.length, self.numVarSelectorRecords)

		return headerdata + data


class cmap_format_unknown(CmapSubtable):

	def toXML(self, writer, ttFont):
		cmapName = self.__class__.__name__[:12] + str(self.format)
		writer.begintag(cmapName, [
				("platformID", self.platformID),
				("platEncID", self.platEncID),
				])
		writer.newline()
		writer.dumphex(self.data)
		writer.endtag(cmapName)
		writer.newline()

	def fromXML(self, name, attrs, content, ttFont):
		self.data = readHex(content)
		self.cmap = {}

	def decompileHeader(self, data, ttFont):
		self.language = 0  # dummy value
		self.data = data

	def decompile(self, data, ttFont):
		# we usually get here indirectly from the subtable __getattr__ function, in which case both args must be None.
		# If not, someone is calling the subtable decompile() directly, and must provide both args.
		if data is not None and ttFont is not None:
			self.decompileHeader(data, ttFont)
		else:
			assert (data is None and ttFont is None), "Need both data and ttFont arguments"

	def compile(self, ttFont):
		if self.data:
			return self.data
		else:
			return None

cmap_classes = {
		0: cmap_format_0,
		2: cmap_format_2,
		4: cmap_format_4,
		6: cmap_format_6,
		12: cmap_format_12,
		13: cmap_format_13,
		14: cmap_format_14,
}
